1. Field of the Invention
This invention relates, in general, to mensuration devices and, in particular, to layout tools which incorporate some measurement facility such as a foldable and/or extensible-retractable measuring tape. Of paramount importance in the instant combination is the novel T-square which serves as a highly utilitarian builder's layout tool.
2. Discussion of Relevant Art
Many layout, leveling, measuring and squaring tools have, over the years, incorporated adjunct tools such as plumb bobs, protractors, bubble levels, squaring devices and extensible-retractable tapes. Many invariably use index lines or indices, lubber lines or other forms of indicia for effecting linear and angular measurements.
A combination tool is disclosed by Ford in 1961 as U.S. Pat. No. 3,008,238; it teaches a compact square, level and steel tape combination tool. The Ford tool is a rectangular cased extensible-retractable tape measure which has a fold out edge that provides a flange means enabling the tape case-with-flange to be used as a squaring device. The compactness of this device, in that the square arms or members cannot be extended, limits the Ford tool. In 1968, Andrews was issued U.S. Pat. No. 3,364,581 for a dual squaring tool. Andrews teaches a grooved ruler which has mounted thereon, in slidable registry, a squaring head from which extends a concavo-convex tape measure, which when extended forms a stiff, rectilinear rule. The dual square head of the Andrews device is obliquely angled giving the device a facility to act as a surface gage.
Like the foregoing Andrew's tool, that disclosed by Showers in 1971 as U.S. Pat. No. 3,568,322 reveals an essentially flat, rectangular case containing an extensible-retractable tape measure, a plumb bob on an extensible-retractable line, a pivotal scriber arm and a non-pivotal fixed, transverse bar used for creating a straight edge reference. Like the aforementioned patents, that issued to Showers reveals a device that combines several tools, and a large number of parts and appears to require a great deal of dexterity and consummate skill in its application. A less complicated square level measuring tool is disclosed in U.S. Pat. No. 4,700,489, issued to Vasile in 1987. This tool is essentially a plane block containing a superposed block which includes a few bubble devices for leveling, an extensible-retractable tape and an extending, fixable and stiff metal rule. The protruding metal rule, used as the squaring arm, detracts from the compactness of the Vasile tool. Compactness also appears to be the disadvantage of a squaring tape measure case that is disclosed in U.S. Pat. No. 4,965,944 issued in 1992 to Kuze et al. Kuze et al. teach a measuring rule employing a casing which permits marking of lines perpendicular to an edge of a workpiece. It also serves to enable measurement and marking of lines through several angular measurements relative to other reference lines. The case of Kuze et al. is characterized by a compact, tape enclosure having two straight edges at right angles and an arcuate edge completing the case enclosure from the ends of the straight, perpendicular edges. On one of the straight edges, there are short extension flanges which, from a top plane view of the case, appears to form a stylized T, having a thick broad upright and very short, narrow and oppositely extending arms. The T-forming flanges enable a right angle scribing. The arms of the T shape are fixed and do not provide a great enough length to serve as a straight edge as one might find in any of the foregoing square or rigid rule type devices.
In order to overcome the limitations and disadvantages of earlier relevant art, I developed my combination layout tool over several iterations in order to ensure the combination of a compact layout tool, with extensible-retractable measuring facility, that would serve primarily as a carpenters square, but of a T shape. The latter is more often a tool of choice used by designers and draftsman, rather than carpenters or builders in general. In this respect, my invention, although adapted for layout usage, employs a somewhat unorthodox shape and method of application.